This week's book giveaway is in the Agile and Other Processes forum.We're giving away four copies of The Little Book of Impediments (e-book only) and have Tom Perry on-line!See this thread for details.

notes: 1 Another method calls GetData after Validate has been instantiated. 2 The Sort seems to work. I have other test code to print the list before and after the sort. 3 Originally I was using Comparators. I would like to sort and search by several properties. But the problem first appeared then, so I simplified.

Please use code tags round your quoted code; they make it easier to read. Please tell us which line the class cast exception occurs on. You should be able to work that out by reading the stack trace which prints out on screen.